Electrolytic condenser



May 7, 1940- s. RUBEN ELECTROLYTIC CONDENSER Filed sept. so, "51937INVENTOR Bfamufjuflz ATTORNEY .Patented Mey 7, 1940 UNITED STATES PATENTori-Ica 2,199,441' e amcfraounc coNDaNsEa samuel aubea'New Boehme. N. Y.l Application september so, 1931, serai No. 166,548

claim. (ci. 11s- 315) This invention relates to dry electrolytic con-.-densers, and more particularly to spacer elements employed therein.

`An object of the invention is the provision of 5 an improved compositespacer element comprising'.` two or more sheet materials cementedtogether. s

A further object is the provision of an adhesive material for cementingtwo or more condenser spacers into one sheet.

Another object is the provision of an adhesive. especially suitable foreementing non-brous and ilbrous sheet spacers so as to allow their usein composite form in -the'manufacture of dry electrolytic condensers.

vFurther objects will be apparent from the disclosure and from thedrawing in which Fig. 1 shows a spacer element; Fig.. 2 illustrates across section of the spacer shown in Fig. 1; Fig. 2o 3 shows a spacerelement wound in coil form between two electrodes to form a condenserunit, and Fig. 4 shows a condenser in coil form mounted within acontainer.

In my United States Letters Patent 1,918,716, I describe a dryelectrolytic 'condenser employing a plasticized and electricallyconductive regenerated cellulose spacer such as cellophane. The spacersreferred to in this application are for use in condensers of the typedescribed in that patent. f

The use of a cellophane spacer in dry electrolytic condensers permitsthe application of potentials beyond that possible with paper or gauzetype spacers. 'I'he non-pervious, ,-non-ilbrous character of thecellulose forces a uniform distribution of current over the entirecontacting electrode and prevents localization of current in any onearea when high' potentials are applied or where higher operatingtemperatures are encountered or utilized. These advantages are somewhatreduced because the contact between the aluminum electrodes andCellopha-ne" is not quite as satisfactory as with fibrous materials andbecause cellophane is more dimcult to impreg- 45 nate than paper orgauze. y To improve the contact and facilitate impregnation acombination of Q "cellophane and paper, or cellophane and gauze has beenused. However, the use of such combinations involves additionalmachinery and 50 added cost of manufacture due to the extra care whichis required in winding the added rolls with the two rolls of ioil andtwo rolls of spacer.

I have found that by cementing the spacers; for instance one layer ofcellophane and one u layer oi' paper, or one layer of cellophane and onelayer of gauze, or one layer of "cellophane" sandwiched between twopapers, `a composite spacer is obtained whichA can be `'employed inplace of single lspacers without the addition of extra rolls and whichmay'be woundinto con- 5 densers by the methods now generally employed.Although a large number of materials can be used to cement thecellophane and paper, -o1" hard and soft paper, the importantrequirement in an adhesive for this purpose is to provide the l0 Aproperchemical and electrical properties. The -f cementing agent must bemisclble and compatible with the types of electrolytes used in dryelectrolytic condensers, for example, ammonium glycol borateelectrolytes, and must not contain ions l5 that will tend to reduce thesparking potential of the anode illm or bring about corrosion of theelectrodes. Such an adhesive must also assist or allow the cellophane"or paper to become as conductive as possible so as to permit a low powerfactor.

In order to meet these requirements I have developed a cementing agentcomprising a water soluble gum, such as gum arabic, and an aqueousmixture of tri-ethylene glycol. The preferred v proportions which allowpractical handling without excessive distortion of the cellophane andprovide necessary electrical conditions, are 50 grams of powdered gumarabic, U. S. P., dissolved in 200 c. c. of distilled water containing20 c. c. of ,30 tri-ethylene glycol, maintained at 90 C. until a clearhomogeneous mixture is obtained. 'These proportions may, of course, bechanged depending upon the consistency desired, degree of heat whichwill be applied to the cemented materials, etc. In the preparation of aspacer comprising a sheet of cellophane between two sheets of paper, theCe1lophane" is passed through the adhesive solution and rolled up incontact with the papers, and thereafter through a drying oven. o Thecomposite spacer is then ready'for winding with the condenser foilarmatures. In the case of a nat type condenser, only one spacer isrequired, but in the case of the conventional roll type condenser, twoof the composite spacers are required. After the condenser has beenrolled it can be impregnated with electrolyte. the porous character ofthe paper insuring the presence of an adequate quantity of electrolyteover the oper` ating life of the condenser.

The particular example given above describes the use of the adhesive ina spacer comprising a sheet of cellophane between two sheets of paper,but the adhesive may also be used in the following laminated spacerconstructions: two u sheets oi.' hard or soft paper; one sheet of hardpaper and one sheet oi' soft paper; one sheet of hardpaper between twosheets of soft paper; one sheet of cellophane and one sheet o1' paper;one sheet of Cellophane and one sheet of gauze; one sheet of cellophanebetween two sheets of gauze.

'I'he presence of the tri-ethylene glycol in the adhesive serves toplasticize and keep the Cellophane in a moist condition, at the sametime facilitating impregnation of the cellophane and paper by theelectrolyte and thereby providing good electrical conductivity from theelec-` trodes through the spacers. While ethylene glycol or glycerinecan be substituted for the trlethylene glycol, they are not assatisfactory as they do not insure the permanent moist condition broughtlabout by the latter, Pure gum tragacanth or chloride free mannitol canbe substituted for gum arabic, but the latter is preferred.

In order to afford a detailed description oi' the spacer and of thecondenser using the spacer, reference is made to the accompanyingdrawing in which similar numerals indicate similar parts.

In Fig. 1, the spacer element I consists of nonbrous regeneratedcellulose sheet 2, cemented between soft porous paper sheets 3 and l, bythe tri-ethylene glycol-gum arabic adhesive described above and shown inexaggerated form at l in Fig. 2.

The coiled condenser construction of Fig. 3 shows spacers l, woundbetween aluminum electrode foils 6 and 1.

In Fig. 4, rthe condenser unit 8, similar to the condenser shown in Fig.3, is mounted within aluminum container 3 and insulatedI therefrom bypitch I0. Cathode tab Il, is grounded to the wall or the container whichacts as the negative terminal, and anode tab I2, is connected totermina] Il, which extends through "Bakelite top Il, which serves toseal the condenser.

Having described my invention, what I claim as new and desire to secureby Letters Patent, is:

1. A spacer pre-assembly for dry electrolytic condensers comprising atleast two sheets of dry electrolytic condenser spacer material infaceto-iace relation, and an adhesive comprising triethylene glycol anda water soluble gum cementing said sheets together.

2. A spacer pre-assembly for dry electrolytic condensers comprising atleast two sheets of dry 'electrolytic condenser spacer material infaceto-Iace relation, and an adhesive comprising triethylene glycol andgum arabic cementing said sheets together.

3. A spacer pre-assembly for dry electrolytic condensers comprising atleast one sheet of nonfibrous cellulose film and at least one sheet oiflbrous cellulosic material in face-to-face relation, and an -adheslvecomprising tri-ethylene glycol and a water soluble gum cementing saidsheets together.

4. A spacer pre-assembly for dry electrolytic condensers comprising atleast one sheet of non- Ilbrous cellulose lm and at least one sheet offibrous cellulosic material in face-to-face relation, and an adhesivecomprising tri-ethylene.

glycol and gum arabic cementing said sheets together.

5. The method of making dry electrolytic condenser assemblies whichcomprises cementing at least ltwo sheets of condenser spacer materialtogether with a cement comprising a polyhydric alcohol and a watersoluble gum and subsequently winding said cemented spacer between twosheet metal electrodes at least one of which is of film-forming metaland then impregnating SAMUEL RUBEN.

the assembly with a nlmmaintaining electrolyte. y

